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Questions of safety manual

Yang ShunFan
Intellectual 570 points
Other Parts Discussed in Thread: TMS570LS1114

Dear all,

Excuse. Our project is planning to use TMS570LS1114.

Now, I am reading the safety manual which as follow:

“Safety Manual for TMS570LS12x and 11x Hercules™ ARM ® Safety Critical Microcontrollers”

http://www.ti.com/lit/ug/spnu550/spnu550.pdf

There is an appendix in the last page, which is TI’s recommendation for each safety items. I have some confusion on it. Could you explain what is the difference between safety feature or diagnostic and possible latent diagnostics?

According to my opinion, safety feature or diagnostic is a primary diagnostic, and possible latent diagnostics is secondary diagnostic. It is used to enhance and strength primary diagnostic. Is it right?

  • 0
    TI__Mastermind 23000 points

    Hello,

    Please note that the table introduction text includes a link to section 5 where this terminology is explained:

    Depending on the safety standard and end equipment targeted, it may be necessary to manage not only
    single point faults, but also latent faults. Per ISO 26262:2011, the latent faults to be considered are when
    the faults in a function are both present: the capability to violate a safety goal and to cause a fault in the
    safety mechanism. Latent fault testing does not need to occur during the fault tolerant time interval, but
    can be performed at boot time, at shut down, or periodically as determined by the system developer. Many
    of the safety mechanisms described in this section can be used as primary diagnostics, diagnostics for
    latent fault, or both. When considering system design for management of latent faults, take care to include
    failure of CPU and memories in consideration for any primary diagnostic that is executed via software.

    In other words, the latent fault column provides a suggestion of what diagnostics can be applied to satisfy the latent fault metric defined in ISO 26262.

    Best Regards,

    Karl Greb